The present invention relates to an electromagnetic actuator such as a linear motor having stationary and movable elements and, more particularly, to an exposure apparatus having the electromagnetic actuator, a device manufacturing method using the exposure apparatus, a device manufacturing factory where the exposure apparatus is installed, and a maintenance method for the exposure apparatus.
Typical, conventional exposure apparatuses used for the manufacture of various devices, such as a semiconductor device, are a step and repeat exposure apparatus (also called a stepper) for sequentially exposing a plurality of exposure regions on a substrate with the pattern of a master (reticle or mask) while stepping the substrate (wafer or glass substrate), and a step and scan exposure apparatus (also called a scanner) for repeating step movement and scanning exposure to repetitively expose a plurality of regions on a substrate. In particular, the step and scan exposure apparatus uses only a light component relatively close to the optical axis of a projection optical system by restricting a light beam through a slit. This type of exposure apparatus enables higher-precision exposure of a fine pattern with a larger field angle.
These exposure apparatuses comprise stage devices (wafer stage and reticle stage) for moving a wafer and reticle at high speed and aligning them. A general stage driving method adopts a linear pulse motor (linear motor) using the Lorentz force. The use of the linear motor realizes high-speed driving of the stage movable and stationary portions in non-contact with each other and high-precision alignment.
The stage acceleration along with higher-speed (higher-throughput) alignment processing increases more and more. For example, in the step and scan exposure apparatus, the maximum stage acceleration reaches 5xc3x979.81 m/s2 (5G) for the reticle stage and 1xc3x979.81 m/s2 (1G) for the wafer stage. The driving force defined by  less than mass of moving member greater than xc3x97 less than acceleration greater than  becomes very large. This also increases the heat generation amount of a stage driving linear motor, and generated heat is seriously influencing the surroundings. To suppress heat generated from a coil, a coolant has conventionally been caused to flow near the coil. The coolant flowing method includes a method of cooling only a coil support, as shown in FIGS. 6A and 6B, and a method of cooling the entire coil, as shown in FIGS. 7A and 7B. A linear motor shown in FIGS. 6A and 6B and a linear motor shown in FIGS. 7A and 7B schematically represent a linear motor in which a coil 4 is attached to a stationary element 1 to drive a movable element 2. FIGS. 6A and 7A are plan views, and FIGS. 6B and 7B are sectional views taken along the lines D-Dxe2x80x2 and E-Exe2x80x2, respectively. In FIGS. 6A and 6B, a coolant channel 32 is formed partially inside a coil support 33, which partially supports the coil 4, and only the coil support 33 is cooled. In this method, the coil 4 is exposed at portions other than the portions where the coil 4 is supported by the coil support 33, and heat greatly influences the surroundings. In FIGS. 7A and 7B, a coolant channel 32 is formed entirely inside a coil support 33 which supports a whole coil 4, and the whole coil 4 is cooled. In this method, heat less influences the surroundings, compared to the method of cooling only the coil support, as shown in FIGS. 6A and 6B. However, a relatively large temperature difference is generated between the upstream and downstream of the cooling coolant. The surface temperature of the linear motor cannot be made uniform, and the temperature difference influences the surroundings.
The conventional manufacturing process of a semiconductor element such as a VLSI formed from an ultrafine pattern employs a reduction type projection exposure apparatus for projecting a circuit pattern drawn on a mask onto a substrate coated with a photosensitive agent and printing the pattern. With an increase in the mounting density of a semiconductor element, demand has arisen for further micropatterning, and the exposure apparatus is coping with micropatterning.
To achieve high-speed alignment by using the linear motor capable of high-precision alignment, a large driving force must be generated. For this purpose, a large current must be caused to flow through the coil. Causing a large current to flow further increases the heat generation amount of the coil.
In general, a semiconductor exposure apparatus uses an interferometer for high-precision alignment. However, heat generated from a coil increases and fluctuates the temperature near a linear motor or in a stage space where the optical axis of the interferometer and a mirror are installed. This decreases the measurement precision of the interferometer.
It is an object of the present invention to provide an electromagnetic actuator such as a linear motor capable of suppressing the influence of heat generated from a coil in an external space.
It is another object of the present invention to provide an exposure apparatus capable of increasing the alignment speed in exposure, increasing the throughput, performing high-speed alignment, and exposing a fine pattern, a device manufacturing method using the exposure apparatus, a semiconductor manufacturing factory including the exposure apparatus, and a maintenance method for the exposure apparatus.
The present invention provides the following electromagnetic actuator. This electromagnetic actuator is an electromagnetic actuator having stationary and movable elements, comprising a magnet arranged on one of the stationary and movable elements, a coil arranged on the other one of the stationary and movable elements, a first coolant channel formed near the coil, and a second coolant channel formed in or near a surface of at least one of the stationary and movable elements. The present invention may be applied to a movable magnet type electromagnetic actuator, a movable coil type electromagnetic actuator, or another type of electromagnetic actuator.
According to a preferred aspect of the present invention, the first coolant channel is essentially formed to cool the coil, and the second coolant channel is essentially formed to adjust a surface temperature of the electromagnetic actuator.
According to another preferred aspect of the present invention, the electromagnetic actuator preferably further comprises a support which internally supports the coil, the first coolant channel is preferably formed inside the support, and the second coolant channel is preferably formed between the first coolant channel and a surface of the support or in the surface of the support. This electromagnetic actuator is suitable for an electromagnetic actuator in which the stationary element has the coil and the movable element has the magnet.
According to still another aspect of the present invention, the electromagnetic actuator may further comprise a support which supports the magnet, the support may be arranged outside the coil and the first coolant channel so as not to contact the coil and the first coolant channel, and the second coolant channel may be formed between the first coolant channel and a surface of the support or in the surface of the support. This electromagnetic actuator is also suited to an electromagnetic actuator in which the stationary element has the coil and the movable element has the magnet. The first coolant channel is preferably so formed as to surround the coil.
According to still another aspect of the present invention, the electromagnetic actuator preferably further comprises a temperature detector for detecting at least one of a temperature of a coolant flowing through the first coolant channel and a temperature of a coolant flowing through the second coolant channel, a thermo-regulator for adjusting temperatures of coolants supplied to the first and second coolant channels, and a temperature controller for controlling the thermo-regulator on the basis of a detection result of the temperature detector.
Alternatively, the electromagnetic actuator preferably further comprises a temperature detector for detecting a temperature of a surface of the electromagnetic actuator or a temperature near the surface, a thermo-regulator for adjusting temperatures of coolants supplied to the first and second coolant channels, and a temperature controller for controlling the thermo-regulator on the basis of a detection result of the temperature detector. The temperature detector preferably detects a temperature of a coolant flowing through the second coolant channel in addition to the temperature of the surface of the electromagnetic actuator or the temperature near the surface.
According to still another aspect of the present invention, the electromagnetic actuator preferably further comprises a heat insulator arranged outside the second coolant channel or between the first and second coolant channels.
According to still another aspect of the present invention, the first and second coolant channels preferably flow coolants in opposite directions. Alternatively, a plurality of second coolant channels are also preferably formed parallel to each other, and flowing directions of coolants through the plurality of second coolant channels are preferably made opposite to each other every predetermined number of channels. Alternatively, the second coolant channel is also preferably meandered.
The present invention provides an exposure apparatus in which the above electromagnetic actuator is applied to a stage for moving a substrate or master. This exposure apparatus comprises a laser interferometer for measuring a position of the stage, and the second coolant channel can be formed between an optical axis of the laser interferometer and the coil.
The present invention provides a device manufacturing method, comprising the steps of installing manufacturing apparatuses for performing various processes including the above exposure apparatus in a device manufacturing factory, and manufacturing a device by performing a plurality of processes using the manufacturing apparatuses.
According to still another aspect of the present invention, the device manufacturing method preferably further comprises the steps of connecting the manufacturing apparatuses by a local area network, and communicating information about at least one of the manufacturing apparatuses between the local area network and an external network outside the device manufacturing factory. The method preferably further comprises the step of accessing a database provided by a vendor or user of the exposure apparatus via the external network to obtain maintenance information about at least one of the manufacturing apparatuses by data communication. The method preferably further comprises the step of performing data communication between the device manufacturing factory and another device manufacturing factory via the external network to perform production management.
The present invention provides a device manufacturing factory comprising manufacturing apparatuses for performing various processes including the above exposure apparatus, a local area network for connecting the manufacturing apparatuses, and a gateway which enables access from the local area network to an external network outside the factory, wherein information about at least one of the manufacturing apparatuses can be communicated.
The present invention provides a maintenance method for the above exposure apparatus that is installed in a device manufacturing factory, comprising the steps of causing a vendor or user of the exposure apparatus to provide a maintenance database connected to an external network outside the device manufacturing factory, permitting access to the maintenance database from the device manufacturing factory via the external network, and transmitting maintenance information accumulated in the maintenance database to the device manufacturing factory via the external network.
The exposure apparatus preferably further comprises a display, a network interface, and a computer for executing network software, and maintenance information of the exposure apparatus can be communicated via a computer network. The network software preferably enables connecting the computer to the external network outside the factory where the exposure apparatus is installed, providing on the display a user interface for accessing a maintenance database which is provided by a vendor or user of the exposure apparatus, and obtaining information from the database via the external network.
According to the preferred aspects of the present invention, most of the heat from the coil is recovered by the first coolant flowing through a coil cooling coolant channel (first coolant channel). The remaining heat which cannot be recovered by the first coolant is recovered by the second coolant flowing through a temperature adjustment coolant channel (second coolant channel). The overall electromagnetic actuator such as a linear motor can be efficiently cooled. Heat recovery by the second coolant is much smaller than that by the first coolant. The temperature distribution between the upstream and downstream of the coolant can be substantially ignored on the surface of the electromagnetic actuator. The influence of heat in the vicinity of the electromagnetic actuator, particularly the stage space of the exposure apparatus, can be suppressed.
Other features and advantages of the present invention will be apparent from the following description taken in conjunction with the accompanying drawings, in which like reference characters designate the same or similar parts throughout the figures thereof.